1. Field of the Invention
The present invention relates to a broadband ISDN (hereinafter abbreviated B-ISDN) remote multiplexer for connection to an asynchronous transfer mode (ATM) exchange, and more particularly to a simple, compact, and low-cost B-ISDN remote multiplexer wherein the remote multiplexer is constructed by separating a subscriber line interfacing section from an ATM exchange and installing it at a remote location connected via a high-speed transmission line, the connection and other control operations being performed by the ATM exchange.
2. Description of the Related Art
The cost of switching equipment and the cost of subscriber lines connecting the subscribers to the switching equipment are predominant expenses in the construction of a switched network. Therefore, in conventional telephone networks, a technique generally known as remote multiplexing is widely used whereby a large number of subscriber lines are concentrated at a point near the subscribers and multiplexed on a high-speed or broadband transmission line or the like for transmission to a switching station. Since the reduction of the subscriber line cost is one of its purposes, as noted above, the remote multiplexer is required to have a compact and low-cost construction.
The same situation applies to the B-ISDN, and a compact and low-cost construction is required of the remote multiplexer. However, unlike conventional switched network, the B-ISDN involves so-called label multiplexing using fixed-length ATM cells, dropping ATM cells in the event of line congestion, and so on; therefore, the remote multiplexer is required to have such facilities as management of bands assigned for use, management of call status of connected calls, etc. Providing these facilities in the remote multiplexer, however, causes a problem in view of the above-mentioned purpose of reducing the size and cost of the equipment.